In the related art, an optical measuring method using a flow cytometry (flow cytometer) has been employed to analyze cells, microorganisms, and biologically-relevant microparticles such a liposome. The flow cytometer is a device which irradiates microparticles, which flow through a flow path disposed in a flow cell or a microchip, with light. The flow cytometer also detects fluorescence or scattered light emitted from an individual microparticle, and analyzes the fluorescence or the scattered light.
Examples of the flow cytometer include a device having a function of sorting and recovering, based on the analyzed results, only microparticles which have specific characteristics. Especially, a device which targets a cell as an object to be sorted is called a “cell sorter”. Generally, in this cell sorter, fluid discharged from the flow path is converted into fluid droplets by giving oscillation to the flow cell or the microchip with an oscillation element and the like (see Patent Documents 1, 2). The fluid droplets isolated from the fluid are charged with positive (+) or negative (−) charges. Then, traveling directions of the fluid droplets are changed by a deflection plate. After that, the fluid droplets are recovered and put into a predetermined container and the like.
Further, a method has been suggested in the related art as technology for stabilizing sorting performance (see Patent Document 3). In this method, images of fluid or fluid droplets, which are discharged from an outlet nozzle of a flow cell, are taken. Herein, conditions such as pressure including sheath pressure, and crystal drive are adjusted depending on deviations calculated from the images.